well you might want to find software from websites like
http://www.kde-apps.org/
also a lot of programs come with a installation guide
if you don't get the guide then i guess to might want to read a tutorial which to can find probably on this forum or other websites
here is a tip*
if it comes as a rpm then you can simply install with a program called kpackage which comes with KDE
if it is open source then uncompress and use shell and go into the directory
and type
./configure
make
make install
this will install a program for you